I don't think it will. The 757 is now 20 years old, maiden flight was exactly 20 years ago day by day Feb 19 1982, and only 1000 of them have been built compared to over 1800 727's that were built also within 20 years (1964-1984). American recently took delivery of the 1000th 757 built. Even in five years from now the total number of 757 orders won't reach 1800, that I can understand because the NG737's and the A32X, which are the two main narrowbody types in the air transport industry, are being produced in large numbers. True, the 757 was initially designated the successor to the 727, but the NG737's and A320's are also replacing a large number of 727's especially in the United States.
Only two aircrafts in the whole history of civil aviation have beaten the 727: the DC-3 not including the military C-47, and the Classic 737 (100 thru 500 series combined).

It might not at the pace its going it would be another 17 years or so, but today it has alot more competition and their are alot of niche aircraft. Whereas back in 82 all you had was a 722 or a 752 for certain rtes but they might have offered to much capacity, now you can get a 737-700 or 319. They can fly those rtes and be profitable.

Here's my two cents. (thank you for asking by the way) Back when the 757 was launched, I don't think that the "150 seat class" aircraft was really that important as it is today. I think Boeing marketed the 752 as an aircraft that was much cheaper to operate, yet could hold 40 more seats than the 727.

The 757 won't beat the 727, but then, the 757 is really what would be the size of a hypothetical 727-300, rather than a replacement or successor to the 727. The 727 will always be "The Workhorse of the Jet Age."

One thing is clear, though -- the Next-Generation 737's are on pace to be the most successful jetliner family ever, with over 1000 delivered in just four years after the first was delivered to the launch customer, Southwest Airlines.